Bryophytes and ferns of lampenflora in Grotta Gigante (NE Italy)

Lampenflora consists of phototrophic organisms, which grow near artificial light sources in show caves; these communities represent an alteration of the underground environment and may cause damages both to speleothems and cave fauna. A floristic research on the bryophytes and ferns (land plant) of lampenflora of Grotta Gigante (“Giant Cave”, Trieste, NE Italy) was carried out in 2012. 26 sites near artificial lights of different kinds were sampled in the show cave, for a total of 50 floristic releves. 16 moss species and 2 ferns were found; no liverworts were observed. The most common and widespread mosses are Eucladium verticillatum, F issidens bryoides, Oxyrrhynchium schleicheri and Rhynchostegiella tenella; 7 moss species were found only in one to two sampling sites. The fern Asplenium trichomanes is common, with well-developed individuals growing in highly illuminated sites with dripping water; Asplenium scolopendrium in development in one site is a new record for the lampenflora of the cave. Some moss species belong to the flora of natural cave entrances of the Italian Karst, while others are typical of disturbed and open habitats. The main stalagmites of the cave are colonized by Eucladium verticillatum. Small, scattered individuals of 4 moss species and Asplenium trichomanes were observed growing around some LED lamps installed in 2009 along the cave’s pathways. In the artificial tunnel opened to public in 1996 lampenflora is colonizing the walls around the fluorescent lamps fitted in 2009, with 7 species of mosses and small plants of Asplenium trichomanes. Thanks to the long history as a show cave, the absence of chemical treatments to control lampenflora growth and the possibility to date new installation of several lamps, Grotta Gigante represents an interesting case-study of lampenflora.